Production of Cellulase Enzymes by Bacillus subtilis A8 on Agricultural Waste Products Adlay and Foxtail Millet Husks

Abstract

Adlay (Coix lacryma-jobi L.) and foxtail millet husks Setaria italica (L.) P.Beauv are agricultural waste products which are rich in cellulose. Therefore, this research aimed to produce cellulase from Bacillus subtilis A8 through a fermentation process involving adlay and foxtail millet husks as the substrates. The cellulase was tested on carboxy methylcellulose (CMC), substrates of adlay, and foxtail millet husks for certain factors, such as the effect of incubation time, pH, temperature, and dissolved protein levels, as well as the activation or inhibition by metal ions. The result showed optimum activity observed on the CMC during the 3rd day of incubation, which was activated by metal ions of Co2+ and Cu2+ at a pH 6, temperature 60ºC, and dissolved protein level 0.05 µg/mL. Subsequently, optimum activity was observed on the foxtail millet husk during the 3rd day of incubation, which was activated by metallic ions of Co2+ and Cu2+ at a pH 7, temperature 50ºC, and protein level 0.14 µg/mL. Lastly, there was optimum activity observed on the adlay husk substrate, which was activated by metal ions of Co2+ and Cu2+ during incubation on the 3rd day at a pH 7, temperature 60ºC, and protein level 0.15 µg/mL.